"The legislators of Vermont really broke ground on this," said Barbara Coombs Lee, president of Compassion & Choices, to CBSNews.com.

Now it's up to the Vermont Health Department to implement the rules. But it could be some time before the first person is able to take advantage of the law.

For the first three years, the new Vermont law will include a requirement that patients state three times  once in writing  that they wish to die.

"This is the way you make a practice like this safe... you make it transparent, you pass rules about it that are safe and clear and everybody understands, and it's subject to the light of the day and violations are easily perceived. If you keep it undercover in the shadows... that's when we worry an unregulated and underground practice that you can't regulate at all," said Coombs Lee.

"You pass clear laws with clear boundaries and enforce those boundaries, and that's what the Vermont law does," she added.